Integrated transformer

ABSTRACT

A transformer comprises a substrate comprising a semiconductor material, a first conductor over the substrate, a second conductor over the substrate, and a magnetic layer over the substrate. The first conductor defines a generally spiral-shaped signal path having at least one turn. The second conductor defines a generally spiral-shaped signal path having at least one turn.

CROSS REFERENCE TO RELATED APPLICATIONS

This patent application is a divisional patent application of a priorapplication Ser. No. 12/238,418 filed Sep. 25, 2008, which is acontinuation patent application of a prior application Ser. No.10/965,086 filed Oct. 13, 2004, issued as U.S. Pat. No. 7,434,306; whichis a divisional of prior application Ser. No. 10/637,428 filed Aug. 8,2003, issued as U.S. Pat. No. 6,943,658; which is a divisional of priorapplication Ser. No. 10/230,580, filed Aug. 29, 2002, issued as U.S.Pat. No. 6,856,236; which is a divisional of prior application Ser. No.09/853,370 filed May 11, 2001, issued as U.S. Pat. No. 6,870,456; whichis a continuation-in-part patent application of U.S. patent applicationSer. No. 09/766,162, filed Jan. 19, 2001, entitled INTEGRATED INDUCTOR,by Donald S. Gardner, issued as U.S. Pat. No. 6,856,228; which is acontinuation-in-part patent application of U.S. patent application Ser.No. 09/444,608, filed Nov. 23, 1999, entitled METHOD AND APPARATUS FORPROVIDING INDUCTOR FOR INTEGRATED CIRCUIT OR INTEGRATED CIRCUIT PACKAGE,by Donald S. Gardner, issued as U.S. Pat. No. 6,452,247.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to the field of electricaltransformers. More particularly, the present invention relates to thefield of electrical transformers for integrated circuits (ICs) and ICpackages.

2. Description of Related Art

Electrical transformers are typically used in a variety ofmicroelectronic circuit applications such as, for example, powerconverters, power delivery devices, power isolation devices, and radiofrequency (RF) and microwave circuitry including matching networks,oscillators, amplifiers, and filters. Because discrete transformersresult in losses, for example, due to parasitic capacitance andresistance in connecting them to an integrated circuit and becausediscrete transformers incur a relatively high cost for assembly,transformers are preferably fabricated on-chip; that is, integrated onan integrated circuit, and/or in a package housing an integratedcircuit.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is illustrated by way of example and notlimitation in the figures of the accompanying drawings, in which likereferences indicate similar elements and in which:

FIG. 1 illustrates, for one embodiment, a plan view of an integratedinductor;

FIG. 2 illustrates, for one embodiment, a flow diagram to form theintegrated inductor of FIG. 1;

FIG. 3 illustrates, for one embodiment, a cross-sectional view of asubstrate over which a first dielectric layer and a magnetic layer areformed;

FIG. 4 illustrates, for one embodiment, a cross-sectional view of thesubstrate of FIG. 3 after the first magnetic layer has been patternedand a second dielectric layer has been formed;

FIG. 5 illustrates, for one embodiment, a cross-sectional view of thesubstrate of FIG. 4 after the second dielectric layer has been patternedand a conductive layer has been formed;

FIG. 6 illustrates, for one embodiment, a cross-sectional view of thesubstrate of FIG. 5 after the conductive layer has been patterned and athird dielectric layer has been formed;

FIG. 7 illustrates, for one embodiment, a cross-sectional view of thesubstrate of FIG. 6 after the third dielectric layer has been patternedand a second magnetic layer has been formed and patterned;

FIG. 8 illustrates, for one embodiment, a flow diagram to form amagnetic layer;

FIG. 9 illustrates, for one embodiment, a cross-sectional view of asubstrate over which a dielectric layer and a magnetic layer have beenformed;

FIG. 10 illustrates, for one embodiment, a cross-sectional view of thesubstrate of FIG. 9 after a patterned mask layer has been formed and themagnetic layer has been patterned;

FIG. 11 illustrates, for one embodiment, a plan view of an integratedtransformer;

FIG. 12 illustrates, for one embodiment, a cross-sectional view of theintegrated transformer of FIG. 11;

FIG. 13 illustrates, for one embodiment, a plan view of anotherintegrated transformer;

FIG. 14 illustrates, for one embodiment, a plan view of anotherintegrated transformer;

FIG. 15 illustrates, for one embodiment, a plan view of anotherintegrated transformer;

FIG. 16 illustrates, for one embodiment, a plan view of anotherintegrated transformer;

FIG. 17 illustrates, for one embodiment, a block diagram of anintegrated circuit comprising one or more transformers; and

FIG. 18 illustrates, for one embodiment, a block diagram of anintegrated circuit package comprising one or more transformers.

DETAILED DESCRIPTION

The following detailed description sets forth an embodiment orembodiments in accordance with the present invention for an integratedtransformer. In the following description, details are set forth such asspecific materials, parameters, etc. in order to provide a thoroughunderstanding of the present invention. It will be evident, however,that the present invention may be practiced without these details. Inother instances, well-known process steps, equipment, etc. have not beendescribed in particular detail so as not to obscure the presentinvention.

Spiral Inductor Structure

FIG. 1 illustrates, for one embodiment, an integrated inductor 100.Integrated inductor 100 comprises a generally spiral-shaped conductor110 defining a signal path along which current may flow to generate anelectromagnetic field around conductor 110. Current may flow throughconductor 110 by applying a voltage potential across an innermost node112 near the beginning of an innermost turn 114 of conductor 110 and anoutermost node 116 near the end of an outermost turn 118 of conductor110.

Although illustrated as defining approximately 2¾ generallyoctagonal-shaped turns, conductor 110 may define any suitable number ofone or more turns and any suitable fraction of a turn of any suitableshape. Each turn may be rectangular, hexagonal, or circular in shape,for example. Conductor 110 may comprise any suitable conductive materialand may have any suitable dimensions. The signal path defined byconductor 110 may have any suitable width, thickness, and length withany suitable spacing between turns to form a generally spiral-shapedconductor 110 covering an area of any suitable shape and size. As usedin this description, a spiral or spiral-shaped conductor includes anyconductor defining a signal path having at least one turn with eachsuccessive turn, if any, substantially surrounding the innermost turnand any preceding turn.

Inductor 100 for one embodiment comprises a magnetic layer 120.Conductor 110 is positioned over magnetic layer 120 and for oneembodiment is separated from magnetic layer 120 by at least a dielectriclayer. Such a dielectric layer may comprise any suitable dielectricmaterial and have any suitable thickness. The dielectric material andthickness help determine the capacitance and therefore the resonancefrequency ω_(r) for inductor 100. Magnetic layer 120 forms a voltagereference plane for inductor 100 to help contain electric and magneticfields around conductor 110. Magnetic layer 120 therefore helps increasethe inductance L of inductor 100, and therefore the quality factor Q forinductor 100. Magnetic layer 120 may comprise any suitable magneticmaterial and have any suitable shape, such as the rectangular shapeillustrated in FIG. 1 for example, and any suitable dimensions.

Inductor 100 may be designed to have any suitable frequency range andany desirable quality factor Q ∝ ωL/R, where ω is the operatingfrequency for inductor 100, L is the inductance of inductor 100, and Ris the resistance of inductor 100. As the quality factor Q of inductor100 is proportional to the inductance L of inductor 100 and inverselyproportional to the resistance R of inductor 100, inductor 100 can bedesigned with a relatively higher inductance L, and therefore arelatively higher quality factor Q, for a given area or resistance R ofinductor 100. Alternatively, for a given inductance L, inductor 100 canbe designed with a relatively smaller area and therefore a relativelylower resistance R and capacitance, resulting in a relatively higherresonance frequency ω_(r) and a relatively higher quality factor Q.

Inductor 100 for one embodiment is formed over a substrate comprising asemiconductor material with at least a dielectric layer separatingmagnetic layer 120 from the substrate. Such a dielectric layer maycomprise any suitable dielectric material and have any suitablethickness. As conductor 110 generates a magnetic flux toward thesubstrate that would induce Eddy or mirror currents and therefore lossesin inductor 100 and noise in the substrate, positioning magnetic layer120 between the substrate and conductor 110 helps reduce such currentsand minimizes concern for interference between inductor 100 andneighboring circuitry. Magnetic layer 120 also helps prevent substratecoupling and helps reduce substrate dependency.

Magnetic layer 120 for one embodiment defines slots, such as slots 122and 124 for example, to help further reduce any Eddy currents in thesubstrate. Magnetic layer 120 may define any suitable number of one ormore slots with any suitable dimensions and orientation at any suitableone or more locations relative to conductor 110. One or more slots maybe perpendicular to or at any other suitable angle relative to the flowof current through conductor 110. Defining slots in magnetic layer 120also reduces Eddy currents that can form in magnetic layer 120 and helpsto increase the resonance frequency ω_(r) for inductor 100.

Magnetic layer 120 for one embodiment has a relatively high magneticpermeability, a relatively high saturation magnetization, and arelatively high magnetic resonance frequency to allow inductor 110 tooperate at relatively high frequencies, such as in the GigaHertz (GHz)range for example. Permeability is a measure of the ability of amagnetic material to magnetize. A non-magnetic material has a relativepermeability of one. A magnetic material having a relatively highsaturation magnetization allows for relatively high currents to be used.The increase in inductance L due to magnetic layer 120 helps increasethe quality factor Q for inductor 100.

Magnetic layer 120 for one embodiment is compatible with availablesemiconductor processing and packaging technology that may be used toform a chip having inductor 100. That is, magnetic layer 120 may beformed and optionally patterned using available semiconductor processingtechnology and may generally withstand relatively high temperaturesencountered in processing and packaging a chip on which inductor 100 isformed without crystallizing or significantly changing the relevantproperties of magnetic layer 120.

Magnetic layer 120 for one embodiment comprises cobalt (Co). Magneticlayer 120 for one embodiment comprises an amorphous cobalt (Co) alloycomprising cobalt (Co) and any suitable one or more elements of anysuitable atomic or weight percentage. The amorphous cobalt (Co) alloymay have any suitable atomic order. For one embodiment, the amorphouscobalt (Co) alloy has an atomic order in the range of approximately 1angstrom (Å) to approximately 100 angstroms (Å). For one embodiment, theamorphous cobalt (Co) alloy has an atomic order in the range ofapproximately 1 angstrom (Å) to approximately 25 angstroms (Å). For oneembodiment, the amorphous cobalt (Co) alloy has an atomic order in therange of approximately 1 angstrom (Å) to approximately 10 angstroms (Å).

Magnetic layer 120 for one embodiment comprises an amorphous cobalt (Co)alloy comprising cobalt (Co) and zirconium (Zr). Zirconium (Zr) helpsmake cobalt (Co) amorphous. Magnetic layer 120 for one embodimentcomprises a cobalt-zirconium (CoZr) alloy having one or more additionalelements, such as tantalum (Ta) and niobium (Nb) for example, that helpmake the cobalt-zirconium (CoZr) alloy magnetically softer. Magneticlayer 120 for one embodiment comprises a cobalt-zirconium (CoZr) alloyhaving one or more additional elements, such as a rare earth element forexample, that help increase the ferromagnetic resonance of thecobalt-zirconium (CoZr) alloy. Rare earth elements include rhenium (Re),neodymium (Nd), praseodymium (Pr), and dysprosium (Dy) for example.Rhenium (Re) help reduce stress and magnetostriction for thecobalt-zirconium (CoZr) alloy.

Where magnetic layer 120 comprises a cobalt-zirconium (CoZr) alloy,magnetic layer 120 may comprise, for example, approximately 3 atomicpercent to approximately 10 atomic percent zirconium (Zr).

Where magnetic layer 120 comprises a cobalt-zirconium-tantalum (CoZrTa)alloy, magnetic layer 120 may comprise, for example, approximately 3atomic percent to approximately 10 atomic percent zirconium (Zr) and maycomprise up to and including approximately 10 atomic percent tantalum(Ta). Magnetic layer 120 for one embodiment comprises approximately 91.5atomic percent cobalt (Co), approximately 4 atomic percent zirconium(Zr), and approximately 4.5 atomic percent tantalum (Ta). Such a CoZrTaalloy can operate in the GigaHertz (GHz) range and can withstandtemperatures up to approximately 450° Celsius without crystallizing orsignificantly changing its relevant properties.

Where magnetic layer 120 comprises a cobalt-zirconium-rhenium (CoZrRe)alloy, magnetic layer 120 may comprise, for example, approximately 3atomic percent to approximately 10 atomic percent zirconium (Zr) and maycomprise up to and including approximately 3 atomic percent rhenium(Re). Magnetic layer 120 for one embodiment comprises approximately 89atomic percent cobalt (Co), approximately 8 atomic percent zirconium(Zr), and approximately 3 atomic percent rhenium (Re).

Magnetic layer 120 may have any suitable thickness. Magnetic layer 120for one embodiment has a thickness in the range of approximately 0.05microns (μm) to approximately 2.0 microns (μm). Magnetic layer 120 forone embodiment has a thickness in the range of approximately 0.1 microns(μm) to approximately 1.0 micron (μm). Magnetic layer 120 for oneembodiment has a thickness of approximately 0.4 microns (μm).

Inductor 100 for one embodiment comprises another magnetic layerpositioned over conductor 110 and separated from conductor 110 by atleast a dielectric layer. Such a dielectric layer may comprise anysuitable dielectric material and have any suitable thickness. Thedielectric material and thickness help determine the capacitance andtherefore the resonance frequency ω_(r) of inductor 100. The othermagnetic layer may comprise any suitable magnetic material and have anysuitable shape and dimensions similarly as for magnetic layer 120. Theother magnetic layer may or may not comprise the same magnetic materialas magnetic layer 120. The other magnetic layer helps further increasethe inductance L of inductor 100, and therefore the quality factor Q forinductor 100, when used with magnetic layer 120.

The other magnetic layer for one embodiment defines slots to help reduceEddy currents and increase the resonance frequency ω_(r) for inductor100. The other magnetic layer may define any suitable number of one ormore slots with any suitable dimensions and orientation at any suitableone or more locations relative to conductor 110. One or more slots maybe perpendicular to or at any other suitable angle relative to the flowof current through conductor 110.

Inductor 100 may optionally comprise both magnetic layer 120 and theother magnetic layer or only either one of the two magnetic layers. Forone embodiment where inductor 100 comprises both magnetic layer 120 andthe other magnetic layer, magnetic layer 120 and the other magneticlayer may be connected through a region 132 within innermost turn 114 ofconductor 110 and/or at one or more regions, such as regions 134 and 136for example, along a perimeter surrounding outermost turn 118 ofconductor 110. Connecting magnetic layer 120 and the other magneticlayer helps increase the inductance L of inductor 100 and therefore thequality factor Q for inductor 100. Magnetic layer 120 and the othermagnetic layer may be connected along a perimeter of any suitable shape,such as the rectangular shape illustrated in FIG. 1 for example.Connecting magnetic layer 120 and the other magnetic layer at most orsubstantially all regions along a perimeter surrounding conductor 110helps prevent straying of the magnetic flux generated by conductor 110.

Spiral Inductor Fabrication

Inductor 100 may be fabricated in any suitable manner. For oneembodiment, inductor 100 is fabricated in accordance with flow diagram200 as illustrated in FIG. 2.

For block 202 of FIG. 2, a first dielectric layer 302 is formed over asubstrate 300 as illustrated in FIG. 3. The cross-sectional view of FIG.3 generally corresponds to a cross-section at line A-A of inductor 100as illustrated in FIG. 1. Substrate 300 may comprise any suitablesemiconductor material, such as silicon (Si), silicon germanium (SiGe),germanium (Ge), or gallium arsenide (GaAs) for example. Dielectric layer302 may comprise any suitable dielectric material, such as an oxide ofsilicon, silicon nitride, or silicon oxynitride for example, and may beformed to any suitable thickness using any suitable technique.Dielectric layer 302 helps insulate inductor 100 from substrate 300. Forone embodiment, dielectric layer 302 is formed by depositing silicondioxide (SiO₂) over substrate 300 to a thickness of approximately 2microns (μm) using a suitable chemical vapor deposition (CVD) technique.For another embodiment where substrate 300 comprises silicon (Si),dielectric layer 302 may be formed by growing approximately 2 microns(μm) of silicon dioxide (SiO₂) on substrate 300.

Although illustrated in FIG. 3 as forming dielectric layer 302 directlyover substrate 300, dielectric layer 302 may be formed over one or moresuitable layers, such as one or more interconnect, via, dielectric,and/or device layers for example, formed over substrate 300.

For block 204, a magnetic layer 304 is formed over dielectric layer 302as illustrated in FIG. 3. Magnetic layer 304 corresponds to magneticlayer 120 of FIG. 1. Magnetic layer 304 may comprise any suitablemagnetic material and may be formed to any suitable thickness using anysuitable technique. For one embodiment, magnetic layer 304 is formed bysputter depositing an amorphous cobalt (Co) alloy, such as a suitablecobalt-zirconium-tantalum (CoZrTa) alloy for example, to a thickness inthe range of approximately 0.1 microns (μm) to approximately 1.0 micron(μm) over dielectric layer 302. The magnetic material for one embodimentfor magnetic layer 304 may be deposited in the presence of an appliedmagnetic field to induce desirable magnetic properties in magnetic layer304.

For block 206, magnetic layer 304 is patterned to define at least oneslot, such as slot 322 for example, as illustrated in FIG. 4. Magneticlayer 304 may be patterned to define any suitable number of one or moreslots with any suitable dimensions and orientation at any suitable oneor more locations. Magnetic layer 304 for one embodiment is patterned todefine slots having a width in the range of approximately 0.05 microns(μm) to approximately 15 microns (μm). Magnetic layer 304 for oneembodiment is patterned to define a conductive underpass 126 toinnermost node 112 of inductor 110 as illustrated in FIG. 1 to allow avoltage potential to be applied to node 112.

Magnetic layer 304 may be patterned using any suitable patterningtechnique. Magnetic layer 304 for one embodiment is patterned by forminga patterned mask over magnetic layer 304, etching magnetic layer 304 topattern magnetic layer 304 in accordance with the patterned mask, andremoving the patterned mask. The patterned mask may comprise anysuitable material, such as photoresist for example, formed to anysuitable thickness and may be patterned using any suitable technique.Magnetic layer 304 may be etched using any suitable etch technique, suchas a suitable wet etching technique for example.

Forming magnetic layer 304 and/or patterning magnetic layer 304 todefine one or more slots is optional.

For block 208, a second dielectric layer 306 is formed over magneticlayer 304 as illustrated in FIG. 4. Dielectric layer 306 corresponds tothe dielectric layer between magnetic layer 120 and conductor 110 ofFIG. 1 and helps insulate magnetic layer 120 from conductor 110. For oneembodiment where magnetic layer 304 defines one or more slots,dielectric layer 306 fills each such slot. For one embodiment wheremagnetic layer 304 is patterned to define conductive underpass 126,dielectric layer 306 fills the slots surrounding conductive underpass126.

Dielectric layer 306 may comprise any suitable dielectric material, suchas an oxide of silicon, silicon nitride, or silicon oxynitride forexample, and may be formed to any suitable thickness using any suitabletechnique. For one embodiment, dielectric layer 306 is formed bydepositing silicon dioxide (SiO₂) over magnetic layer 304 to a thicknessof approximately 10,000 angstroms (Å) using a tetraethyl orthosilicate(TEOS) silicon dioxide (SiO₂) plasma enhanced chemical vapor deposition(PECVD) system.

For block 210, dielectric layer 306 is patterned to define at least onevia to magnetic layer 304, such as vias 332 and 334 for example, asillustrated in FIG. 5. Dielectric layer 306 for one embodiment ispatterned to define at least one via in region 132 within innermost turn114 of conductor 110 as illustrated in FIG. 1 to connect magnetic layer304 with another magnetic layer. Dielectric layer 306 for one embodimentis patterned to define at least one via in one or more regions, such asregions 134 and 136 for example, along a perimeter surrounding outermostturn 118 of conductor 110 as illustrated in FIG. 1. For one embodimentwhere magnetic layer 304 defines conductive underpass 126 extendingacross the perimeter to node 112 and conductor 110 defines a conductiveconnection extending across the perimeter to node 116, as illustrated inFIG. 1, dielectric layer 306 is not patterned with any via along theperimeter in such regions. For one embodiment where magnetic layer 304defines conductive underpass 126, dielectric layer 306 is patterned toform a via to conductive underpass 126 to connect node 112 to conductiveunderpass 126.

Dielectric layer 306 may be patterned using any suitable patterningtechnique. Dielectric layer 306 for one embodiment is patterned byforming a patterned mask over dielectric layer 306, etching dielectriclayer 306 to pattern dielectric layer 306 in accordance with thepatterned mask, and removing the patterned mask. The patterned mask maycomprise any suitable material, such as photoresist for example, formedto any suitable thickness and may be patterned using any suitabletechnique. Dielectric layer 306 may be etched using any suitable etchtechnique, such as a suitable dry etch technique for example.

Forming dielectric layer 306 is optional. Dielectric layer 306 may notbe formed, for example, where magnetic layer 304 is not formed.Patterning dielectric layer 306 to define one or more vias to magneticlayer 304 is optional. Dielectric layer 306 may not be patterned, forexample, where magnetic layer 304 does not define conductive underpass126 and where magnetic layer 304 is not to be connected to anothermagnetic layer.

For block 212, a conductive layer 308 is formed over dielectric layer306 as illustrated in FIG. 5. For one embodiment where dielectric layer306 defines one or more vias to magnetic layer 304, conductive layer 308fills any such vias.

Conductive layer 308 may comprise any suitable conductive material andmay be formed to any suitable thickness using any suitable technique.Suitable conductive materials include, for example, copper (Cu),aluminum (Al), tungsten (W), molybdenum (Mo), titanium (Ti), gold (Au),silver (Ag), a metal silicide, a metal nitride, polysilicon, or an alloycontaining one or more such conductive materials, such as analuminum-copper (AlCu) alloy, an aluminum-silicon (AlSi) alloy, analuminum-copper-silicon (AlCuSi) alloy, and a titanium nitride (TiN)alloy for example. For one embodiment, conductive layer 308 is formed bysputter depositing an aluminum-copper-silicon (AlCuSi) alloy overdielectric layer 306 to a thickness of approximately 1 micron (μm).

Conductive layer 308 for one embodiment may also be formed to comprisean underlying adhesion and/or diffusion barrier layer and/or anoverlying adhesion and/or diffusion barrier layer. Conductive layer 308for one embodiment may also be formed to comprise any overlying layerthat serves as an anti-reflective coating for lithography and/or thathelps prevent hillocking of the conductive material for conductive layer308. For one embodiment where conductive layer 308 comprises analuminum-copper-silicon (AlCuSi) alloy, a titanium (Ti) layer may bedeposited prior to depositing the aluminum-copper-silicon alloy andanother titanium (Ti) layer may be deposited over the depositedaluminum-copper-silicon alloy.

For block 214, conductive layer 308 is patterned to form conductor 110as illustrated in FIGS. 1 and 6. Conductive layer 308 may be patternedto define a signal path having any suitable width, thickness, and lengthand any suitable spacing between turns to form a generally spiral-shapedconductor 110 covering an area of any suitable shape and size. For oneembodiment where dielectric layer 306 defines one or more vias tomagnetic layer 304, conductive layer 308 is also patterned to removeconductive layer 308 from any such vias. Where magnetic layer 304defines conductive underpass 126, however, conductive layer 308 for oneembodiment is not removed from any via to conductive underpass 126. Inthis manner, conductive layer 308 helps connect conductive underpass 126to node 112 of conductor 110.

Conductive layer 308 may be patterned using any suitable patterningtechnique. Conductive layer 308 for one embodiment is patterned byforming a patterned mask over conductive layer 308, etching conductivelayer 308 to pattern conductive layer 308 in accordance with thepatterned mask, and removing the patterned mask. The patterned mask maycomprise any suitable material, such as a photoresist and a silicondioxide (SiO₂) hard mask for example, formed to any suitable thicknessand may be patterned using any suitable technique. Conductive layer 308may be etched using any suitable etch technique, such as a suitableplasma dry etching technique for example.

For block 216, a third dielectric layer 310 is formed over conductivelayer 308 as illustrated in FIG. 6. Dielectric layer 310 for oneembodiment helps insulate conductive layer 308 from another magneticlayer. Dielectric layer 310 fills the areas removed from conductivelayer 308 in patterning conductive layer 308 to form conductor 110.Dielectric layer 310 also fills any exposed vias in dielectric layer306.

Dielectric layer 310 may comprise any suitable dielectric material, suchas an oxide of silicon, silicon nitride, or silicon oxynitride forexample, and may be formed to any suitable thickness using any suitabletechnique. For one embodiment, dielectric layer 310 is formed bydepositing silicon dioxide (SiO₂) over conductive layer 308 to athickness of approximately 10,000 angstroms (Å) using a tetraethylorthosilicate (TEOS) silicon dioxide (SiO₂) plasma enhanced chemicalvapor deposition (PECVD) system.

For block 218, dielectric layer 310 is patterned to define at least onevia extending to magnetic layer 304 as illustrated in FIG. 7. Dielectriclayer 310 for one embodiment is patterned to define a via extendingthrough each exposed via defined by dielectric layer 306.

Dielectric layer 310 may be patterned using any suitable patterningtechnique. Dielectric layer 310 for one embodiment is patterned byforming a patterned mask over dielectric layer 310, etching dielectriclayer 310 to pattern dielectric layer 310 in accordance with thepatterned mask, and removing the patterned mask. The patterned mask maycomprise any suitable material, such as photoresist for example, formedto any suitable thickness and may be patterned using any suitabletechnique. Dielectric layer 310 may be etched using any suitable etchtechnique, such as a suitable dry etch technique for example.

Forming dielectric layer 310 is optional. Dielectric layer 310 may notbe formed, for example, where another magnetic layer is not to be formedover conductive layer 308. Patterning dielectric layer 310 to define oneor more vias to magnetic layer 304 is optional. Dielectric layer 310 maynot be patterned, for example, where magnetic layer 304 is not formed orwhere magnetic layer 304 is not to be connected to another magneticlayer formed over conductive layer 308.

For block 220, a second magnetic layer 312 is formed over dielectriclayer 302 as illustrated in FIG. 7. For one embodiment where dielectriclayers 306 and 310 define one or more vias to magnetic layer 304,magnetic layer 312 fills any such vias. In this manner, one or moreconnections between magnetic layer 304 and magnetic layer 312 may beformed.

Magnetic layer 312 may comprise any suitable magnetic material and maybe formed to any suitable thickness using any suitable technique. Forone embodiment, magnetic layer 312 is formed by sputter depositing anamorphous cobalt (Co) alloy, such as a suitablecobalt-zirconium-tantalum (CoZrTa) alloy for example, to a thickness inthe range of approximately 0.1 microns (μm) to approximately 1.0 micron(μm) over dielectric layer 310. The magnetic material for one embodimentfor magnetic layer 312 may be deposited in the presence of an appliedmagnetic field to induce desirable magnetic properties in magnetic layer312.

For block 222, magnetic layer 312 is patterned to define at least oneslot, such as slot 342 for example, as illustrated in FIG. 7. Magneticlayer 312 may be patterned to define any suitable number of one or moreslots with any suitable dimensions and orientation at any suitable oneor more locations. Magnetic layer 312 for one embodiment is patterned todefine slots having a width in the range of approximately 0.05 microns(μm) to approximately 15 microns (μm).

Magnetic layer 312 may be patterned using any suitable patterningtechnique. Magnetic layer 312 for one embodiment is patterned by forminga patterned mask over magnetic layer 312, etching magnetic layer 312 topattern magnetic layer 312 in accordance with the patterned mask, andremoving the patterned mask. The patterned mask may comprise anysuitable material, such as photoresist for example, formed to anysuitable thickness and may be patterned using any suitable technique.Magnetic layer 312 may be etched using any suitable etch technique, suchas a suitable wet etching technique for example.

Forming magnetic layer 312 and/or patterning magnetic layer 312 todefine one or more slots is optional.

Although illustrated as using only magnetic material to connect magneticlayer 312 to magnetic layer 304, any suitable conductive material mayalso be used. For one embodiment, any vias in dielectric layer 306 tomagnetic layer 304 may be filled with conductive material in forming andpatterning conductive layer 308 for blocks 212 and 214. Dielectric layer310 may then be patterned for block 218 to define at least one via toany such filled vias. As magnetic material fills any vias in dielectriclayer 310 in forming magnetic layer 312 for block 220, one or moreconnections between magnetic layer 304 and magnetic layer 312 is formed.

Although illustrated as comprising conductive underpass 126 defined bymagnetic layer 304, inductor 100 for another embodiment may also orinstead comprise a similar conductive overpass defined by magnetic layer312 to allow a voltage potential to be applied to node 112.

For another embodiment, inductor 100 may be fabricated such that avoltage potential may be applied to node 112 and/or node 116 frombeneath magnetic layer 304. Also, inductor 100 may be fabricated suchthat a voltage potential may be applied to node 112 and/or node 116 fromabove magnetic layer 312. Nodes 112 and/or 116 may each be conductivelycoupled to circuitry from beneath and/or above inductor 100 by forming arespective via through magnetic layer 304 and/or magnetic layer 312 andfilling the via with a suitable conductive material. For anotherembodiment, a portion of magnetic layer 304 and/or magnetic layer 312may optionally be isolated to serve as a portion of a conductive contactto conductor 110. By conductively coupling both nodes 112 and 116through magnetic layer 304 and/or magnetic layer 312 in this manner,magnetic layers 304 and 312 may be connected continuously along the fullperimeter surrounding outermost turn 118.

For one embodiment where inductor 100 comprises only magnetic layer 304or magnetic layer 312, dielectric layer 306 and/or dielectric layer 310may nevertheless be patterned with at least one via in region 132 and/orin one or more regions along a perimeter surrounding conductor 110, asillustrated in FIG. 1, for subsequent filling with a suitable magneticor conductive material.

Inductor 100 for another embodiment is fabricated using a suitabledamascene process to form conductor 110. Rather than forming andpatterning conductive layer 308, dielectric layer 306 or anotherdielectric layer formed over dielectric layer 306 may be patterned todefine suitable trenches and/or vias such that a conductive material,such as copper (Cu) for example, may be deposited over the dielectriclayer and polished with a suitable chemical-mechanical polishing (CMP)technique, for example, to form conductor 110. One or more vias tomagnetic layer 304 may then be defined through the dielectric layer.

Magnetic Layer Processing

Magnetic layers 304 and 312 may each be formed and patterned in anysuitable manner. For one embodiment, each magnetic layer 304 and 312 isformed and patterned in accordance with flow diagram 800 as illustratedin FIG. 8. Flow diagram 800 is described in the context of magneticlayer 304 for the sake of simplicity.

For block 802 of FIG. 8, an underlying layer 902 is formed overdielectric layer 302 as illustrated in FIG. 9. Layer 902 may serve as anadhesion layer and/or as a diffusion barrier layer for magnetic layer304.

Layer 902 may comprise any suitable material and may be formed to anysuitable thickness using any suitable technique. For one embodimentwhere the magnetic material for magnetic layer 304 comprises anamorphous cobalt (Co) alloy, such as cobalt-zirconium-tantalum (CoZrTa)for example, titanium (Ti) may be sputter deposited over dielectriclayer 302 to a suitable thickness, such as approximately 250 angstroms(Å) for example, using a physical vapor deposition (PVD) system, forexample, to form layer 902. Titanium (Ti) helps the cobalt (Co) alloyadhere to dielectric layer 302.

Layer 902 is optional and may not be used, for example, where adhesionand/or diffusion are of minimized concern for the magnetic material ofmagnetic layer 304.

For block 804 of FIG. 8, a magnetic material layer 904 is formed overunderlying layer 902 as illustrated in FIG. 9. Magnetic material layer904 may comprise any suitable material and may be formed to any suitablethickness using any suitable technique.

Magnetic material layer 904 for one embodiment comprises cobalt (Co).Magnetic material layer 904 for one embodiment comprises an amorphouscobalt (Co) alloy comprising cobalt (Co) and any suitable one or moreelements of any suitable atomic or weight percentage. The amorphouscobalt (Co) alloy may have any suitable atomic order. For oneembodiment, the amorphous cobalt (Co) alloy has an atomic order in therange of approximately 1 angstrom (Å) to approximately 100 angstroms(Å). For one embodiment, the amorphous cobalt (Co) alloy has an atomicorder in the range of approximately 1 angstrom (Å) to approximately 25angstroms (Å). For one embodiment, the amorphous cobalt (Co) alloy hasan atomic order in the range of approximately 1 angstrom (Å) toapproximately 10 angstroms (Å).

Magnetic material layer 904 for one embodiment comprises an amorphouscobalt (Co) alloy comprising cobalt (Co) and zirconium (Zr). Zirconium(Zr) helps make cobalt (Co) amorphous. Magnetic material layer 904 forone embodiment comprises a cobalt-zirconium (CoZr) alloy having one ormore additional elements, such as tantalum (Ta) and niobium (Nb) forexample, that help make the cobalt-zirconium (CoZr) alloy magneticallysofter. Magnetic material layer 904 for one embodiment comprises acobalt-zirconium (CoZr) alloy having one or more additional elements,such as a rare earth element for example, that help increase theferromagnetic resonance of the cobalt-zirconium (CoZr) alloy. Rare earthelements include rhenium (Re), neodymium (Nd), praseodymium (Pr), anddysprosium (Dy) for example. Rhenium (Re) helps reduce stress andmagnetostriction for the cobalt-zirconium (CoZr) alloy.

Where magnetic material layer 904 comprises a cobalt-zirconium (CoZr)alloy, magnetic material layer 904 may comprise, for example,approximately 3 atomic percent to approximately 10 atomic percentzirconium (Zr).

Where magnetic material layer 904 comprises a cobalt-zirconium-tantalum(CoZrTa) alloy, magnetic material layer 904 may comprise, for example,approximately 3 atomic percent to approximately 10 atomic percentzirconium (Zr) and may comprise up to and including approximately 10atomic percent tantalum (Ta). Magnetic material layer 904 for oneembodiment comprises approximately 91.5 atomic percent cobalt (Co),approximately 4 atomic percent zirconium (Zr), and approximately 4.5atomic percent tantalum (Ta). Such a CoZrTa alloy can operate in theGigaHertz (GHz) range and can withstand temperatures up to approximately450° Celsius without crystallizing or significantly changing itsrelevant properties.

Where magnetic material layer 904 comprises a cobalt-zirconium-rhenium(CoZrRe) alloy, magnetic material layer 904 may comprise, for example,approximately 3 atomic percent to approximately 10 atomic percentzirconium (Zr) and may comprise up to and including approximately 3atomic percent rhenium (Re). Magnetic material layer 904 for oneembodiment comprises approximately 89 atomic percent cobalt (Co),approximately 8 atomic percent zirconium (Zr), and approximately 3atomic percent rhenium (Re).

Magnetic material layer 904 may be formed to any suitable thickness.Magnetic material layer 904 for one embodiment has a thickness in therange of approximately 0.05 microns (μm) to approximately 2.0 microns(μm). Magnetic material layer 904 for one embodiment has a thickness inthe range of approximately 0.1 microns (μm) to approximately 1.0 micron(μm). Magnetic material layer 904 for one embodiment has a thickness ofapproximately 0.4 microns (μm).

Magnetic material layer 904 for one embodiment is sputter depositedusing a physical vapor deposition (PVD) system, for example. Magneticmaterial layer 904 for one embodiment is deposited in the presence of anapplied magnetic field to induce desirable magnetic properties inmagnetic material layer 904. Magnetic material layer 904 may bedeposited, for example, in the presence of a fixed magnetic field, anapproximately 180° switching magnetic field, or an orthogonal switchingmagnetic field.

Magnetic material layer 904 for one embodiment may be deposited insublayers of any suitable thickness, such as approximately 0.2 microns(μm) for example, to help prevent overheating and crystal growth duringdeposition. Each sublayer for one embodiment may be deposited in thepresence of a magnetic field in such a manner so as to induce a magneticanisotrophy in the sublayer in a direction parallel to the plane of thesublayer and orthogonal to that of another sublayer. Each sublayer may,for example, be deposited in the presence of an orthogonal switchingmagnetic field. Substrate 300 may also be repositioned relative to afixed magnetic field as each sublayer is deposited so as to induce theorthogonal magnetic fields.

For block 806 of FIG. 8, an overlying layer 906 is formed over magneticmaterial layer 904 as illustrated in FIG. 9. Layer 906 may serve as anadhesion layer, a diffusion barrier layer, and/or as an anti-reflectivecoating for lithography for magnetic layer 304. Layer 906 may compriseany suitable material and may be formed to any suitable thickness usingany suitable technique.

For one embodiment where magnetic material layer 904 comprises cobalt(Co), titanium (Ti) may be sputter deposited over magnetic materiallayer 904 to a suitable thickness, such as approximately 250 angstroms(Å) for example, using a physical vapor deposition (PVD) system, forexample, to form layer 906. Titanium (Ti) helps photoresist adhere tocobalt (Co) in patterning magnetic layer 304, helps protect cobalt (Co)from relatively high temperature processes that could potentiallyoxidize the top surface of magnetic material layer 904 and possiblydamage the relevant properties of cobalt (Co), and may help reduce anyundercutting in etching magnetic material layer 904.

For another embodiment where magnetic material layer 904 comprisescobalt (Co), magnetic material layer 904 is oxidized to form layer 906comprising cobalt oxide (CoO_(x)). Cobalt oxide (CoO_(x)) may be formedto any suitable thickness, such as in the range of approximately 10angstroms (Å) to approximately 100 angstroms (Å) for example. Magneticmaterial layer 904 for one embodiment is briefly ashed with a suitablerelatively low lamp, low temperature recipe to oxidize cobalt (Co) whileminimizing any damage to the relevant properties of cobalt (Co).Oxidizing cobalt (Co) in this manner helps photoresist adhere to cobalt(Co) in patterning magnetic layer 304.

Layer 906 is optional and may not be used, for example, where adhesionis of minimized concern for the magnetic material of magnetic layer 304.

For block 808, a patterned mask layer 908 is formed over magnetic layer304 as illustrated in FIG. 10. Mask layer 908 may comprise any suitablematerial and may have any suitable thickness. Mask layer 908 may bepatterned using any suitable technique. Mask layer 908 for oneembodiment comprises photoresist that is spun on and then patterned byexposing mask layer 908 through a suitable mask and developing masklayer 908.

For block 810, underlying layer 902, magnetic material layer 904, andoverlying layer 906 are etched as illustrated in FIG. 10. Magnetic layer304 for one embodiment is etched using a suitable wet etching technique.For one embodiment where layer 906 comprises titanium (Ti) or cobaltoxide (CoO_(x)), a suitable dilute hydrofluoric (HF) acid solution isused to etch layer 906 exposed by mask layer 908. For one embodiment, anapproximately 50:1 HF acid solution is used. For one embodiment wheremagnetic material layer 904 comprises cobalt (Co), a solution of nitricacid is used to wet etch magnetic material layer 904 exposed by masklayer 908. For one embodiment, an approximately 10% solution of nitric(HNO₃) acid is used. For one embodiment where layer 906 comprisestitanium (Ti), layer 906 helps reduce any undercutting in wet etchingmagnetic material layer 904. For one embodiment where layer 902comprises titanium (Ti), a suitable dilute hydrofluoric (HF) acidsolution is used to etch layer 902 exposed by mask layer 908. For oneembodiment, an approximately 50:1 HF acid solution is used.

As substrate 300 is further processed in accordance with flow diagram200 of FIG. 2, for example, each subsequent process technique is toaccount for the presence of magnetic layer 304. As one example wheremagnetic layer 304 comprises cobalt (Co), exposing magnetic layer 304 toa plasma or atmosphere containing oxygen at relatively high temperaturesmay damage the relevant properties of magnetic layer 304. The effects ofsubsequent process techniques on magnetic layer 304 may be monitoredusing a permeance meter, for example.

For one embodiment where magnetic layer 304 comprises cobalt (Co),silicon dioxide (SiO₂) is deposited to form dielectric layer 306, forexample, using a suitable plasma enhanced chemical vapor deposition(PECVD) system with tetraethyl orthosilicate (TEOS) to help maintain atemperature below approximately 450° Celsius and therefore help minimizeany oxidation and crystallization of magnetic layer 304.

For one embodiment where photoresist, for example, is to be removed frommagnetic layer 304, dielectric layer 306, and/or from a silicon dioxide(SiO₂) hard mask over conductive layer 308, a suitable relatively lowtemperature resist strip technique and a suitable solvent may be usedinstead of a typical relatively high temperature ash technique to avoidexposing magnetic layer 304 to plasmas at relatively high temperaturesfor relatively long periods of time. For another embodiment wherephotoresist, for example, is used in etching silicon dioxide (SiO₂),such as for dielectric layer 306 for example, the silicon dioxide (SiO₂)may be etched using a suitable relatively low power and relatively lowtemperature dry etch technique to help minimize any hardening of thephotoresist. The photoresist may then be removed using a suitablesolvent.

Following fabrication of inductor 100 with magnetic layer 304 and/ormagnetic layer 312, magnetic layer 304 and/or magnetic layer 312 may beannealed by exposing inductor 100 to a suitable temperature in thepresence of a magnetic field to help vitalize the magnetic properties ofmagnetic layer 304 and/or magnetic layer 312.

Although described in the context of inductor 100 as illustrated in FIG.1, one or more magnetic layers may be formed and possibly patterned infabricating other suitable inductors having other suitable structures.As one example, inductor 100 may be fabricated with a multi-levelconductor formed across multiple layers and/or with multiple conductors.Inductor 100 for one embodiment may be formed with multiple conductorscoupled in series or in parallel. Also, one or more magnetic layers maybe formed and possibly patterned in fabricating other suitableintegrated circuit devices, such as an integrated transformer formedusing one or more inductors similar to inductor 100.

Integrated Transformer Structure and Fabrication

FIG. 11 illustrates, for one embodiment, an integrated transformer 1100.FIG. 12 illustrates, for one embodiment, a cross-sectional view ofintegrated transformer 1100. The cross-sectional view of FIG. 12generally corresponds to a cross-section at line 12-12 of transformer1100 as illustrated in FIG. 11.

As illustrated in FIG. 12, integrated transformer 1100 comprisesintegrated inductor 100 and another integrated inductor 1150 formed overinductor 100. Integrated inductor 1150 for one embodiment is similarlyfabricated as inductor 100. Inductor 100 corresponds to a primary coilof a conventional transformer, and inductor 1150 corresponds to asecondary coil. As inductors 100 and 1150 are electrically isolated fromone another, transformer 1100 for one embodiment may be used to couplesignals or power from one circuit to another while isolating directcurrent (dc) biases. Transformer 1100 may also be used to help reducenoise.

As illustrated in FIG. 12, inductor 1150 comprises, similarly asinductor 100, a generally spiral-shaped conductor 1160 defining a signalpath along which current may flow. Inductor 1150 is positioned relativeto inductor 100 such that an electromagnetic field generated by inductor100 induces a voltage potential across an innermost node 1162 near thebeginning of an innermost turn 1164 of conductor 1160 and an outermostnode 1166 near the end of an outermost turn 1168 of conductor 1160.Current then flows through conductor 1160. The induced voltage potentialacross inductor 1150 may be stepped up or stepped down from the voltagepotential applied across inductor 100 as desired in designing inductors100 and 1150 and in positioning inductors 100 and 1150 relative to oneanother.

Although each conductor 110 and 1160 is illustrated as definingapproximately 2¾ generally octagonal-shaped turns, each conductor 110and 1160 may define any suitable number of one or more turns and anysuitable fraction of a turn of any suitable shape. Each turn may berectangular, hexagonal, or circular in shape, for example. The number ofturns defined by each conductor 110 and 1160 helps determine the amountof the voltage potential induced across inductor 1150 for a givenvoltage potential applied across inductor 100. The shape of each turnfor each conductor 110 and 1160 may also help determine the amount ofthe voltage potential induced across inductor 1150 for a given voltagepotential applied across inductor 100.

Each conductor 110 and 1160 may comprise any suitable conductivematerial and may have any suitable dimensions. The signal path definedby each conductor 110 and 1160 may have any suitable width, thickness,and length with any suitable spacing between turns and may cover an areaof any suitable shape and size. The material and dimensions of eachconductor 110 and 1160 and the spacing between turns for each conductor110 and 1160 may help determine the amount of the voltage potentialinduced across inductor 1150 based on a given voltage potential appliedacross inductor 100.

Inductors 100 and 1150 may be positioned relative to one another in anysuitable manner to induce any desirable voltage potential acrossinductor 1150 for a given voltage potential applied across inductor 100.Inductor 1150 for one embodiment is positioned relative to inductor 100such that the signal path defined by conductor 1160 lies over and isgenerally parallel to the signal path defined by conductor 110. Howinductors 100 and 1150 are positioned relative to one another and theproximity between inductors 100 and 1150 helps determine the amount ofthe voltage potential induced across inductor 1150 based on a givenvoltage potential applied across inductor 100.

Although described in the context of inductor 100 corresponding to aprimary coil and inductor 1150 corresponding to a secondary coil,inductor 100 may also correspond to a secondary coil and inductor 1150may correspond to a primary coil. That is, a voltage potential may beapplied across nodes 1162 and 1166 of inductor 1150 to generate anelectromagnetic field around both inductors 1150 and 100 and induce avoltage potential across nodes 112 and 116 of inductor 100.

Inductors 100 and 1150 for one embodiment are each fabricated to have anincreased self-inductance to help increase the quality factor Q of eachinductor 100 and 1150 and to help form transformer 1100 with arelatively high mutual inductance between inductors 100 and 1150.

As illustrated in FIG. 12, inductor 1150 for one embodiment is similarlyfabricated as inductor 100. Inductor 1150 comprises magnetic layer 312,a first dielectric layer 314, a conductive layer 316 to form conductor1160, a second dielectric layer 318, and a magnetic layer 320. Magneticlayer 312 serves as a second magnetic layer for inductor 100 and as afirst magnetic layer for inductor 1150. Dielectric layer 314 helpsinsulate conductive layer 316 from magnetic layer 312. Dielectric layer318 helps insulate magnetic layer 320 from conductive layer 316.

Inductor 1150 for one embodiment is fabricated in accordance with flowdiagram 200 as illustrated in FIG. 2. After inductor 100 has beenformed, dielectric layer 314 may be formed over inductor 100 andpatterned similarly as dielectric layer 306 for blocks 208 and 210 ofFIG. 2. Forming and/or patterning dielectric layer 314 is optionalsimilarly as dielectric layer 306. Dielectric layer 314 may not beformed, for example, where inductor 100 does not comprise magnetic layer312 and does comprise dielectric layer 310.

Conductive layer 316 may be formed and patterned to form conductor 1160similarly as conductive layer 308 for blocks 212 and 214 of FIG. 2.

Dielectric layer 318 may be formed and patterned similarly as dielectriclayer 310 for blocks 216 and 218 of FIG. 2. Forming and/or patterningdielectric layer 318 is optional similarly as dielectric layer 310.

Magnetic layer 320 may be formed and patterned similarly as magneticlayer 312 for blocks 220 and 222 of FIG. 2. Forming and/or patterningmagnetic layer 320 is optional similarly as magnetic layer 312.

Magnetic layers 304 and/or 312 help increase the self-inductance ofinductor 100, and magnetic layers 312 and/or 320 help increase theself-inductance of inductor 1150. Magnetic layers 304, 312, and/or 320help increase the mutual inductance between inductors 100 and 1150. Eachmagnetic layer 304, 312, and 320 may comprise any suitable magneticmaterial and have any suitable shape, such as the rectangular shapeillustrated in FIGS. 1 and 11 for example, and any suitable dimensions.Each magnetic layer 304, 312, and 320 may or may not comprise the samemagnetic material as any other magnetic layer 304, 312, or 320. Any oneor more of magnetic layers 304, 312, and 320 may optionally define anysuitable number of one or more slots.

Transformer 1100 for one embodiment may optionally comprise one ofmagnetic layers 304, 312, and 320 to help increase the inductance ofinductor 100 and/or inductor 1150. Transformer 1100 for anotherembodiment may optionally comprise two of magnetic layers 304, 312, and320 to help further increase the inductance of inductor 100 and/orinductor 1150. Transformer 1100 for another embodiment may comprise allthree magnetic layers 304, 312, and 320 to help even further increasethe inductance of inductor 100 and/or inductor 1150.

For one embodiment where transformer 1100 comprises two or more ofmagnetic layers 304, 312, and 320, each such magnetic layer 304, 312, or320 may optionally be connected to another magnetic layer 304, 312, or320 with any suitable magnetic and/or conductive material. Magneticlayers 304 and 312 may be connected, as illustrated in FIG. 1, through aregion 132 within innermost turn 114 of conductor 110 and/or at one ormore regions, such as regions 134 and 136 for example, along a perimetersurrounding outermost turn 118 of conductor 110. Magnetic layers 312 and320 may be connected, as illustrated in FIG. 11, through a region 1182within innermost turn 1164 of conductor 1160 and/or at one or moreregions, such as regions 1184 and 1186 for example, along a perimetersurrounding outermost turn 1168 of conductor 1160. Magnetic layers 304and 320 may be connected through regions 132 and 1182 and/or at one ormore regions, such as regions 134 and 1184 and regions 136 and 1186 forexample, along a perimeter surrounding conductors 110 and 1160. Two ormore of magnetic layers 304, 312, and 320 may be connected along aperimeter of any suitable shape, such as the rectangular shapeillustrated in FIGS. 1 and 11 for example.

Connecting two or more of magnetic layers 304, 312, and 320 helpsincrease the self-inductance of inductor 100 and/or inductor 1150 andthe mutual inductance between inductor 100 and 1150. Connecting two ormore of magnetic layers 304, 312, and 320 at most or substantially allregions along a perimeter surrounding conductor 110 and/or conductor1160 helps prevent straying of the magnetic flux generated by conductor110 and/or conductor 1160.

FIG. 13 illustrates, for one embodiment, another integrated transformer1300. Integrated transformer 1300 comprises integrated inductor 1310 andanother integrated inductor 1360. As illustrated in FIG. 13, inductors1310 and 1360 are positioned in a side-by-side relationship. As inductor1310, for example, generates an electromagnetic field due to theapplication of a voltage potential across inductor 1310, a voltagepotential is induced across inductor 1360. The induced voltage potentialacross inductor 1360 may be stepped up or stepped down from the voltagepotential applied across inductor 1310 as desired in designing inductors1310 and 1360 and in positioning inductors 1310 and 1360 relative to oneanother.

Each inductor 1310 and 1360 for one embodiment is fabricated similarlyas inductor 100. For one embodiment, each inductor 1310 and 1360 isfabricated in accordance with flow diagram 200 of FIG. 2 over the samesubstrate to form transformer 1300.

For one embodiment where each inductor 1310 and 1360 comprises a firstmagnetic layer corresponding to magnetic layer 304 of inductor 100, eachcorresponding first magnetic layer of inductors 1310 and 1360 for oneembodiment may be formed at the same time and remain connected to oneanother to help increase the mutual inductance between inductors 1310and 1360. For one embodiment where each inductor 1310 and 1360 comprisesa second magnetic layer corresponding to magnetic layer 312 of inductor100, each corresponding second magnetic layer of inductors 1310 and 1360for one embodiment may be formed at the same time and remain connectedto one another to help increase the mutual inductance between inductors1310 and 1360. For one embodiment where each inductor 1310 and 1360comprises both magnetic layers corresponding to magnetic layers 304 and312 of inductor 100, the first magnetic layer of each inductor 1310 and1360 may be connected to the second magnetic layer of each inductor 1310and 1360 at one or more regions along a perimeter surrounding bothinductors 1310 and 1360 to help further increase the mutual inductancebetween inductors 1310 and 1360.

FIG. 14 illustrates, for one embodiment, another integrated transformer1400. Integrated transformer 1400 comprises integrated inductor 1410 andanother integrated inductor 1460. Inductors 1410 and 1460 for oneembodiment are positioned such that at least a portion of one or moreturns of the conductor of inductor 1460 are each positioned adjacent toan inner side of at least a portion of one turn of the conductor ofinductor 1410. Inductors 1410 and 1460 for one embodiment are positionedsuch that at least a portion of one or more turns of inductor 1410 areeach positioned between at least a portion of each of two turns ofinductor 1460 and such that at least a portion of one or more turns ofinductor 1460 are each positioned between at least a portion of each oftwo turns of inductor 1410. For one embodiment, as illustrated in FIG.14, inductors 1410 and 1460 are positioned such that each turn ofinductor 1410 is positioned on the same level as and adjacent to atleast one turn of inductor 1460 and such that each turn of inductor 1460is positioned on the same level as and adjacent to at least one turn ofinductor 1410.

As inductor 1410, for example, generates an electromagnetic field due tothe application of a voltage potential across inductor 1410, a voltagepotential is induced across inductor 1460. The induced voltage potentialacross inductor 1460 may be stepped up or stepped down from the voltagepotential applied across inductor 1410 as desired in designing inductors1410 and 1460 and in positioning inductors 1410 and 1460 relative to oneanother.

Each inductor 1410 and 1460 for one embodiment is fabricated similarlyas inductor 100. For one embodiment, each inductor 1410 and 1460 isfabricated in accordance with flow diagram 200 of FIG. 2. The conductorof each inductor 1410 and 1460, for one embodiment, is formedsimultaneously for blocks 212 and 214 of FIG. 2. Transformer 1400 may beformed with a first magnetic layer corresponding to magnetic layer 304of inductor 100 and/or a second magnetic layer corresponding to magneticlayer 312 of inductor 100.

Although each inductor 100, 1150, 1310, 1360, 1410 and 1460 is describedas comprising one single-level spiral-shaped conductor, other suitableprimary and secondary inductors each having any suitable number of oneor more spiral-shaped conductors each formed over one or more levels andcoupled in series or in parallel may be similarly fabricated as inductor100 and positioned relative to one another in any suitable manner toform an integrated transformer.

FIG. 15 illustrates, for one embodiment, another integrated transformer1500. Integrated transformer 1500 comprises integrated inductor 1510 andanother integrated inductor 1560. Inductors 1510 and 1560 for oneembodiment are positioned such that at least a portion of one or moreturns of the conductor of inductor 1560 are each positioned adjacent toan inner side of at least a portion of one turn of the conductor ofinductor 1510 and such that at least a portion of one or more turns ofinductor 1510 are each positioned adjacent to an inner side of at leasta portion of one turn of inductor 1560. Inductors 1510 and 1560 for oneembodiment are positioned such that at least a portion of one or moreturns of inductor 1510 are each positioned between at least a portion ofeach of two turns of inductor 1560, such that at least a portion of oneor more turns of inductor 1560 are each positioned between at least aportion of each of two turns of inductor 1510, and such that each of oneor more turns of inductor 1510 or 1560 crosses over an adjacent turn ofinductor 1560 or 1510 at least once.

As inductor 1510, for example, generates an electromagnetic field due tothe application of a voltage potential across inductor 1510, a voltagepotential is induced across inductor 1560. The induced voltage potentialacross inductor 1560 may be stepped up or stepped down from the voltagepotential applied across inductor 1510 as desired in designing inductors1510 and 1560 and in positioning inductors 1510 and 1560 relative to oneanother.

Each inductor 1510 and 1560 for one embodiment is fabricated similarlyas inductor 100. For one embodiment, each inductor 1510 and 1560 isfabricated in accordance with flow diagram 200 of FIG. 2. The conductorof each inductor 1510 and 1560, for one embodiment, is formedsimultaneously for blocks 212 and 214 of FIG. 2 and spans multiplelevels to accommodate cross-overs for each conductor with a suitabledielectric material between each conductor at each cross-over.Transformer 1500 may be formed with a first magnetic layer correspondingto magnetic layer 304 of inductor 100 and/or a second magnetic layercorresponding to magnetic layer 312 of inductor 100.

Although each transformer 1100, 1300, 1400, and 1500 is illustrated ascomprising one primary inductor and one secondary inductor, any suitablenumber of primary and secondary inductors each similarly fabricated asinductor 100 may be positioned relative to one another in any suitablemanner to form an integrated transformer. As one example, two secondaryinductors may be positioned relative to one primary inductor in anysuitable manner to form an integrated transformer.

Integrated Autotransformer Structure

FIG. 16 illustrates, for one embodiment, an integrated transformer 1600.Integrated transformer 1600 is an autotransformer. Transformer 1600 forone embodiment may be similarly fabricated as inductor 100 of FIG. 1,for example. As a voltage potential is applied across a node 1612 nearone end of a spiral-shaped conductor 1610 of transformer 1600 andanother node 1616 near the other end of conductor 1610, a voltagepotential between any two points along conductor 1610 may be tapped.Transformer 1600 may be used, for example, for circuits such as in adirect current (dc) voltage converter.

FIG. 16 illustrates, for one embodiment, voltage taps 1642 and 1644 eachat a node between nodes 1612 and 1616. A voltage potential tapped usingvoltage taps 1642 and/or 1644 may be stepped down from the voltagepotential applied across transformer 1600 as desired in designingtransformer 1600. The resulting voltage potential, for example, acrossvoltage tap 1642 and voltage tap 1644, node 1612 and voltage tap 1642,node 1612 and voltage tap 1644, node 1616 and voltage tap 1642, and/ornode 1616 and voltage tap 1644 may be tapped.

For another embodiment, a predetermined voltage potential, such asground for example, may be applied to voltage tap 1642 and/or voltagetap 1644. As a voltage potential is applied across transformer 1600, theresulting voltage potential across node 1612 and voltage tap 1642, node1612 and voltage tap 1644, node 1616 and voltage tap 1642, and/or node1616 and voltage tap 1644 may be tapped.

Although conductor 1610 is illustrated as defining approximately 2¾generally octagonal-shaped turns, conductor 1610 may define any suitablenumber of one or more turns and any suitable fraction of a turn of anysuitable shape. Each turn may be rectangular, hexagonal, or circular inshape, for example. The number of turns defined by conductor 1610 helpsdetermine the amount of the voltage potential tapped using voltage taps1642 and/or 1644 for a given voltage potential applied acrosstransformer 1600. The shape of each turn for conductor 1610 may alsohelp determine the amount of the voltage potential tapped using voltagetaps 1642 and/or 1644 for a given voltage potential applied acrosstransformer 1600.

Conductor 1610 may comprise any suitable conductive material and mayhave any suitable dimensions. The signal path defined by conductor 1610may have any suitable width, thickness, and length with any suitablespacing between turns and may cover an area of any suitable shape andsize. The material and dimensions of conductor 1610 and the spacingbetween turns for conductor 1610 may help determine the amount of thevoltage potential tapped using voltage taps 1642 and/or 1644 for a givenvoltage potential applied across transformer 1600.

Transformer 1600 may be fabricated such that a voltage potential may betapped from conductor 1610 in any suitable manner. Transformer 1600 maybe fabricated, for example, such that a voltage potential may be tappedfrom beneath conductor 1610 and/or from above conductor 1610. Voltagetaps 1642 and 1644, for example, may be conductively coupled tocircuitry from beneath and/or above transformer 1600 by forming arespective via to conductor 1610 and filling the via with a suitableconductive material. Where transformer 1600 comprises a lower magneticlayer and/or an upper magnetic layer, a portion of the lower magneticlayer and/or the upper magnetic layer may optionally be isolated toserve as a portion of a conductive contact to conductor 1610.

Although transformer 1600 is described as comprising one single-levelspiral-shaped conductor, any other suitable transformer having anysuitable number of one or more spiral-shaped conductors each formed overone or more levels and coupled in series or in parallel may be similarlyfabricated and tapped at any suitable location along any conductor ofthe transformer.

Although transformer 1600 is illustrated in the context of a singleinductor, any suitable primary or secondary inductor of any suitabletransformer, such as transformer 1100 of FIG. 11, transformer 1300 ofFIG. 13, transformer 1400 of FIG. 14, or transformer 1500 of FIG. 15,for example, may be tapped at any suitable location along any conductorof the transformer.

Integrated Circuit and Integrated Circuit Package

As illustrated in block diagram form in FIG. 17, one or more integratedtransformers 1702 may be integrated in an integrated circuit 1700 withany suitable one or more integrated circuit devices, such as integratedcircuit devices 1704 and 1706 for example, or with any suitable circuitscomprising one or more integrated circuit devices, such as integratedcircuit devices 1704 and 1706 for example. Each transformer 1702 may befabricated, for example, as transformer 1100 of FIG. 11, transformer1300 of FIG. 13, transformer 1400 of FIG. 14, transformer 1500 of FIG.15, or transformer 1600 of FIG. 16. Although illustrated as comprisingtwo transformers 1702, integrated circuit 1700 may be fabricated withany suitable number of one or more transformers 1702.

As illustrated in block diagram form in FIG. 18, one or more integratedtransformers 1802 for one embodiment may be mounted in an integratedcircuit package 1800 for conductive coupling to an integrated circuit1804 housed by integrated circuit package 1800. Each transformer 1802may be integrated with or mounted in integrated circuit package 1800 andconductively coupled to integrated circuit 1804 in any suitable manner.Each transformer 1802 may be fabricated, for example, as transformer1100 of FIG. 11, transformer 1300 of FIG. 13, transformer 1400 of FIG.14, transformer 1500 of FIG. 15, or transformer 1600 of FIG. 16.Although illustrated as comprising two transformers 1802, integratedcircuit package 1800 may be fabricated with any suitable number of oneor more transformers 1802. Also, one or more transformers 1802 may befabricated directly on an integrated circuit package.

In the foregoing description, the invention has been described withreference to specific exemplary embodiments thereof. It will, however,be evident that various modifications and changes may be made theretowithout departing from the broader spirit or scope of the presentinvention as defined in the appended claims. The specification anddrawings are, accordingly, to be regarded in an illustrative rather thana restrictive sense.

1. A transformer comprising: a substrate comprising a semiconductormaterial; a first conductor over the substrate, the first conductordefining a generally spiral-shaped signal path having at least one turn;a second conductor over the substrate, the second conductor defining agenerally spiral-shaped signal path having at least one turn, wherein atleast a portion of the at least one turn of the first conductor ispositioned adjacent to at least a portion of the at least one turn ofthe second conductor; and a first magnetic layer between the substrateand the conductors, wherein the at least one turn of the first conductorcrosses over the at least one turn of the second conductor.
 2. Thetransformer of claim 1, wherein the at least one turn of the firstconductor is positioned on the same level as the at least one turn ofthe second conductor.
 3. The transformer of claim 1, comprising at leastone slot in the first magnetic layer.
 4. The transformer of claim 1,further comprising a second magnetic layer over the conductors.
 5. Thetransformer of claim 1, wherein the magnetic layer comprises cobalt.